No sound from tweeter bx5a
First of all, never connect the audio from your receiver directly to the tweeter. You can blow the tweeter instantly. The mid-bass driver can be damaged from a direct connection as well.
Since you get absolutely no sound from either driver, this seems to implicate the crossover. If the crossover has opened, no signal gets through, if it has opened early in the signal path.
But, it is also possible that a short exists, and that perhaps your amp cuts off the output having sensed a short. The short could be in the crossover or one of the drivers.
Here are some troubleshooting tips--
To prevent damage to your amp, turn it off while making or breaking any connections inside the speaker boxes.
Write down which wires get connected to which place on the drivers, so you can get them back where they belong.
With your amp turned off, connect the bad speaker to your amp. You've already verified that no sound is produced when both drivers are connected.
So, with your amp off, disconnect one wire from the tweeter in the bad box.
Briefly turn your amp on and listen for sound.
If you get sound, the tweeter is shorted.
If you get no sound, with the amp off, reconnect the tweeter in the bad box and disconnect one wire from the mid-bass driver.
Briefly turn the amp on and listen before turning the amp off.
If you get sound now, but not before, the mid-bass driver is shorted.
If you got no sound either way, check the DC resistance of the mid-bass driver (only, not the tweeter. Ohmmeters put out a small DC voltage to test resistance. That DC voltage might damage a tweeter, maybe. Don't risk it). Ohm the mid-bass driver while it is not connected to the crossover. If the driver is good, you should read some ohms--a little less than the stated impedance. An 8 ohm driver might read 6.5 ohms, for instance. If you get an open or a short (with the crossover disconnected from the mid-bass driver) you have a blown driver. Two actually, since neither the tweeter nor the mid-bass driver produced any sound in the previous tests.
If you can't get ahold of an ohmmeter, try this--
Open the good, working speaker and place the two side by side.
Connect your amp to the bad speaker box only.
With your amp turned off, disconnect the wires from the mid-bass driver in the bad box and connect them to the mid-bass driver in the good box. Disconnect one of the wires from the "good" mid-bass driver first, so you don't have two crossovers connected to it at the same time--even if only one of them will get powered on. It keeps the confusion down to a minimum when trying to isolate your problem. Oh, and disconnect one wire from the bad tweeter, in case it is shorted.
Turn the amp on and listen briefly before turning the amp off.
If you got sound, the "bad" crossover is fine, but the "bad" mid-bass driver is blown. And, since you got no sound in the previous tests, the "bad" tweeter is blown, as well.
If you got no sound, try it the other way around. Meaning--
With the amp off, disconnect the speaker wires coming from your amp from the bad speaker box and connect them to the good speaker box.
Your amp is now connected only to the good speaker box.
With the amp still off, connect the mid-bass wires from the good box to the mid-bass driver in the bad box. Remember to disconnect one of the "bad" crossover wires from its own driver first, so only one crossover is connected to the "bad" mid-midbass driver. Remember to disconnect one wire from the "good" and "bad" tweeters, so the only sound you hear--if any--is from the "bad" mid-bass driver, powered by the "good" crossover.
If this produces sound, but the previous attempts failed, you have a crossover problem.
If you still get no sound, something went wrong and you need to retest the good speaker by itself and back up a few steps and try again.
Assuming you got sound from the "good" crossover while it was driving your "bad" mid-bass, make sure no wires have come loose inside the "bad" box. Assuming you have sound connections at each end of each wire, you now need to desolder the electrolytic capacitors from the circuit board.
Make sure you mark them first, so you can put them back where they belong.
You can remove only one at a time, if that helps.
Use an ohmmeter to check some components.
The big red coil should read pretty close to a short, maybe one ohm.
The capacitors should read open or infinite resistance, although you might see a steadily increasing resistance while the capacitor charges up from the ohmmeter. If you read a steady low resistance on a capacitor after it has been removed from the circuit board, that capacitor is bad and must be replaced. The markings on the capacitor should give you some clues as to the proper replacement.
All things considered, I suspect that your problem is a shorted electrolytic capacitor. But, I gave you all I could think of so you can narrow it down and isolate the problem, whatever it might be.
I hope this helps.